[clang] [clang][Darwin] Remove legacy framework search path logic in the frontend (PR #120149)

[Louis Dionne via cfe-commits]

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@@ -8265,6 +8265,11 @@ def internal_externc_isystem : Separate<["-"], "internal-externc-isystem">,
            "implicit extern \"C\" semantics; these are assumed to not be "
            "user-provided and are used to model system and standard headers' "
            "paths.">;
+def internal_iframework : Separate<["-"], "internal-iframework">,
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ldionne wrote:

I see. But there is no notion of "extern C" for framework includes, so IMO it makes more sense to make `-internal-iframework` "equivalent" to `-internal-isystem` than to `-internal-externc-isystem`, would you agree?

More generally, I guess I am confused about the desired grouping for framework includes. Do we want them to be `IncludeDirGroup::System`, `IncludeDirGroup::ExternCSystem` or something else? IIUC, `-iframework` is already part of `IncludeDirGroup::System`. If that's correct, then why is it not sufficient to pass these system framework paths using `-iframework` directly in the first place (i.e. why do we even need to introduce `-internal-iframework` in the first place)?

https://github.com/llvm/llvm-project/pull/120149